Diazonamide A is a mitotic spindle-disrupting agent first isolated from the marine organism Diazona angulata, having the structure:

The preparation of diazonamide analogs via macrocyclic indoline intermediates bearing a carbobenzyloxy (Cbz) or o-nitrophenylsulfonyl protected amino group has been previously described. U.S. Pat. No. 7,022,720 correctly discloses the structure of diazonamide A and describes the synthesis of some of its analogs. U.S. application Ser. No. 11/264,502, a continuation-in-part of U.S. application Ser. No. 10/227,509 (now U.S. Pat. No. 7,022,720) was filed 31 Oct. 2005, and is published as US 2006/0089397. U.S. Ser. No. 11/591,016, a continuation-in-part of U.S. application Ser. No. 11/264,502, was filed 31 Oct. 2006, and is published as US 2007/0149583. U.S. application Ser. No. 12/134,984, filed 6 Jun. 2008, and published as US 2009/0005572, describes synthetic methods for the preparation of diazonamide analogs via indoline intermediates.
It has surprisingly been found that indoline compounds of formula (I), which lack the rigid macrocyclic structure bridging the A- and E-rings of the diazonamide skeleton, possess potent cytotoxic activity and are useful for the treatment of cell proliferative disorders.